Add an Amp or Integrated to AVR?

I recently went through my third set of HT separates and decided to quit chasing the one-thing-does-everything-great setup and simplify by getting a Denon 3806 AVR. I've had Sherbourn, Aragon, Gemstone, Proceed, etc amps and Parasound Halo, Outlaw pre/pros. I have ACI Jaguar/LFM main speakers and want to use the Denon for HT and then improve on my 2-channel sound. I'm not too concerned about driving the the other channels with the Denon....except maybe the center, but that is a lower priority.

What will deliver a bigger improvement in my sound: an integrated amp like a Mac 6500, Krell 400xi, etc. or a 2-channel amp added to the AVR, something like a Parasound A21, Bryston 4b-ST, etc. ?? Obviously with an integrated, the source would run direct to that whereas an amp with the Denon would use the Denon as the pre-amp.

I'd like to keep the cost to $1500, but would be willing to splurge up to $2500 if necessary.

An important point is that the speakers only see a signal from 100Hz and above because the internal crossover sends info below that to the self-powered LFMs. Therefore, deep bass control is less important than good mid-range and high-range performance. The Jags probably lean a bit toward the warm side of neutral...but not by much.

Any help or insight would really be appreciated.
There is no question that an integrated will give you better sound than adding a separate amp.
I've been down that road before and ended up going back to two seperate systems. I'm sure you can find a two channel amp that exceeds the performance of the Denon but there are two probelms with that approach that I've found:

(a) The amp may be limited by the receiver's abilities as a standalone preamp, and

(b) Denon does not currently offer a seperate amplifier (except for one integrated) and therefore you'll be choosing an amp that's voiced differently. That won't be a problem -- until you watch a movie or listen to multichannel music. Then you may notice a (possibly distracting) difference in the character of the sound from the front speakers and the others.

Marantz may offer a 2-channel amp in their reference line that would probably be voiced close to the Denon. And of course, there's always the Audiogon classifieds.

Having owned a Denon AVR-2802, I find that the premp section is rather warm and laid-back, just like the amp section, and lacks detail and definition when seperated out, so a rather lively amp is probably what's called for. But they're your ears.

Last suggestion: why not just sell the Denon and move up to a top of the line HT receiver in the $3000-$5000 range? At least then, you can count on good 2-channel performance without the complication of adding a seperate amp.
You both seem to confirm some comments I've gotten before. Adding the integrated will yield the greatest 2-channel sonic benefit. I'll probably go that route when I see the right unit come available. I've think I narrowed it to the Mac 6500, Krell 400xi and the PS Audio GCC-250. They're all different so I'll probably stick with the one that fits best with my speakers.

I don't want to invest any more in a better AVR because the technology in them is changing so fast that in 6 months you end up with something that has depreciated so much you lose a major portion of your investment. I also think you aren't going to gain that much better sound. An amp or integrated gets you more performance, for less money and holds its value better.

Now I just have to wait for the right integrated to come up. I might just buy a Bryston 3B-ST for the interim, while looking for the right integrated.
In case anyone is interested, I decided to add a Bryston 3-channel 5B-ST to the Denon 3806. I figured this is a safe move for now as they hold their value well and will allow me to try the amp only route rather than springing for a integrated that I'd be happy with.
I'm back at it trying to improve my 2-channel sound. Thinking about adding a pre with a HT bypass in combination with the 5B-ST. That way my front 3 will still be voiced the same, but still get me out of the 3806 as a preamp. Crazy????